Mona

There’s nothing quite as satisfying as seeing massive damage numbers over your enemies. Mona excels at making this happen thanks to an Elemental Burst that can drastically buff a follow-up attack. As a Hydro Catalyst character, she can constantly barrage with element damage and inflict the Wet status on enemies.
Her unique sprint that moves quicker over water is notably useful too. For those like me who love exploring but hate having to cross long stretches of water, Mona helps a lot. Just remember that she needs to start sprinting on land first before transitioning to the water.